1. Field of Invention
The present invention relates to a method of dynamically adjusting an image frame rate, especially a method of dynamically adjusting an image frame rate according to a sensed displacement or a usage time of a reference block. A device using the method is also disclosed by the present invention.
2. Description of Related Art
Image sensing devices are often used in electronic devices such as remote controller, computer mouse, etc. In image sensing operation, image frame rate is a key factor which affects the sensing accuracy and power consumption. When the image frame rate is relatively higher, the sensing accuracy is relatively better but the power consumption is relatively higher. When the image frame rate is relatively lower, the power consumption is relatively lower but the sensing accuracy is relatively lower. Therefore, it is better for the image frame rate to be adjustable so that the needs for sensing accuracy and power consumption can both be met.
One prior art method adjusts the image frame rate by comparing a speed of the image sensing device with a threshold value. The speed is calculated by a calculating unit according to displacements and the image frame rate of the image sensing device. This prior art requires complex calculation and the mechanism to determine whether to adjust the image frame rate is also very complex. Further, the threshold value to be compared with the speed is predetermined, but the motion of a sensed object is usually random, so the predetermined threshold value is often not the best setting.
In view of the aforementioned drawback of the prior art, the present invention discloses a method of dynamically adjusting an image frame rate according to the sensed displacement or the usage time of a reference block, which can improve the overall calculation efficiency, achieving both good sensing accuracy and low power consumption without complicated calculation and complex mechanism for judgment.